a) Field of the Invention
The present invention relates to an apparatus called "drum press extractor" for extracting liquids from a slurry formed of liquids and fibers. The word "slurry" as used hereinafter includes the combination of liquids and fibers with or without other solids. This term also includes wet fibers or any similar product.
b) Brief Description of Prior Art
In the stock-farming industry, it is of common practice to recycle separated farm animal manure as a compost and, if sufficiently dry, as a litter or green bedding for stock animals. Even when the manner is stored in large ponds, it is highly desirable to separate the fibers In order to reduce thick crust build-up over the ponds and thus facilitate agitation and increase storage capacity.
To achieve such a separation, it is of common practice to dilute the manure with water and then let It slide down by gravity along a screen. The liquids and very fine sediments pass through the screen and are collected under the same while the remaining portion of the manure consisting of wet fibers and some coarse sediments, is collected at the bottom of the screen and then used as such or processed through liquids extractor.
Such liquids extractor preferably consists of a "wringing machine" having a main roller and one or more auxiliary rollers whose external surfaces consist of a thin screen with perforations small enough to prevent fibers from passing through. The main and auxiliary rollers are mounted so that the fibers are squeezed between the main roller and each auxiliary roller consecutively. The dry manure fibers are collected at the bottom of the machine while the liquids extracted by the squeezing are collected within the auxiliary rollers and drained out of the same through conduits. So far, the auxiliary rollers used are commonly made of a thin screen mounted on disks themselves mounted on a shaft. These disks have openings to let the collected liquids move toward a conduit located on one or both sides of the auxiliary rollers.
A main problem with the existing "wringing machine" is that, because of the structure of the auxiliary rollers of the existing machine, it is impossible to apply a sufficient pressure onto the same without risking to deform and/or even damage the thin screens that are held only by the peripheries of the supporting discs.
Another problem with the existing machine is that a large amount of water is required to dilute the manure before letting it slide down along the screen and processing it through the machine.
A further problem with the existing machine is that the overall separation performance is reduced due to a "rewatering" of the separated fibers which occur when the fibers which have just been squeezed, act as a sponge and reabsorb liquid through the perforations of the screens of the auxiliary rollers which, as aforesaid, are very thin.